The present invention relates to a controller and method of operating a climate control system including a primary and a secondary heating and cooling source with humidity control. More specifically, the present invention is a controller and method of providing heating and cooling to a zoned residence or building, from a primary source of heat, such as a radiant heating system, and a secondary source of heat, such as a forced air HVAC system. The HVAC system preferably provides primary and secondary cooling as well as humidity control.
Many small businesses and homes utilize a zoned radiant heating system to heat the individual zones during periods of cold outside temperatures, such as during the winter months. In a radiant heating system, a supply of heated water is distributed through a series of heat exchanging pipes positioned throughout the heating zone. For example, a radiant heating system can include radiant floor pipes and baseboard mounted radiators which transfer heat from the supply of heated water to the open environment being controlled.
In a zoned radiant heating system, a controller receives heating demand signals from individual zone thermostats and controls the operation of the main boiler, injection system, a number of water circulators and series of zone controlling devices such as valves or circulators to supply the heated water from the boiler to the individual zones requiring heat. Although radiant heating systems are effective at maintaining a very constant temperature within a heating environment, radiant heating systems often suffer from the inability to quickly heat a room upon a sudden demand for heat, such as when the outside temperature drops dramatically, when the radiant heating system is initially turned on, or when a window has been left open and the temperature within one of the heating zone drops dramatically.
In a small business or residence that utilizes radiant heating, a forced air HVAC system that includes a full zone venting infrastructure and numerous zone dampers to control the flow of air into the zones is installed to provide air conditioning. The HVAC forced air system includes its own separate controller that receives cooling demand signals from the zone thermostats such that the forced air controller controls the operation of the chiller and the opening and closing of the zone dampers to provide cooling to the residence as required. Typically, the control unit for the forced air HVAC system is separate from the control unit for the radiant heating system. Since the controllers of the two systems operate independently, the combined climate control system includes a switch that allows the homeowner to select either the heating and cooling functions.
In a residence or small businesses that has both a radiant heating system and a forced air HVAC system, the forced air HVAC system is used exclusively for cooling. Although it is used only for cooling in this type of application, the forced air HVAC system can also include a heat source to provide heat to the residence. Since radiant heating is a more preferred type of heat, the HVAC forced air system normally does not utilize the forced air heating capabilities. One primary reason for this is the inability for the forced air controller to communicate and coordinate the heating function with the controller for the radiant heating system.
As discussed above, one draw back of a radiant heating system is the inability of the radiant heating system to quickly elevate the temperature in the building to the desired temperature upon a sudden demand for heat. Although the radiant heating system is able to elevate the temperature in a building a few degrees in an acceptable amount of time, situations which require a large temperature rise require an increased amount of time compared to a forced air heating system.
Therefore, it is an object of the present invention to provide a controller that is capable of simultaneously operating both a radiant heating system and a forced air HVAC system based on signals received from a series of zone thermostats. Further, it is an object of the present invention to operate the combined radiant and forced air HVAC systems in a manner such that the forced air system is used to supplement the heat provided by the radiant system when the radiant system is unable to meet the heating demand within a preselected time period. In addition, it is an object of the present invention to operate both the primary and secondary heating and cooling systems, along with humidity, from one thermostat per zone. Further, it is an object of the present invention to provide a controller that allows zones within a facility to be designated as radiant-only and receive heating while other zones in the same building are simultaneously receiving cooling.